if you tried sport climbing, you know that when taking in rope you need to follow the four/ five-step belay procedure. can somebody who had been doing that suddenly change habit to doing the ''one-step'' belay i.e. taking in rope, letting go of the hand and using the same one to taking in rope again?
mindlessly changed?

l suppose with practice. We were out at a popular guide wall this summer when l first saw the new belay method, l actually thought the guy was doing something wrong & went to help. The guide came over & politely thanked me, then explained that this is the new style of teaching a person to belay. His explanation made sense as u have more control at the lock off more of the time. Admittedly, l will still continue to belay the way that l have for the last 20 years, (old habits r hard to break). Heck, even throwing in a body belay when my second is scrambling up a class 4 or 5.0 finish.

l think the point of a good belayer is to never let yourself stop thinking about what the climber is going to do next. If you feel like you may have trouble maintaining this concentration, there are other belay devices/techniques that can aid this. check out a ''Cinch'' or a Gri-Gri! Rock climbing is a very mental game you know.